Expose ability to capture output for use elsewhere
Push command args up from cli helper to client.
Make the run specs work without need to shell out.
Update HISTORY.md
Merge pull request #92 from robincurry/patch-1

Update HISTORY.md, add cli specs, surface :capture_output method in the logger
Rename Report to Result

Improves semantics as a first step toward decoupling the measuring of metric
"results" and the formatting of those results into "reports" (or whatever).
Test that data yml is created during run.
Add basic formatters.
Create reporter to notify configured formatters.
Replicate current report behavior in HTMLFormatter
Remove Result methods that have been moved to formatter
Configure formatters.
Allow formatters/templates to use custom output.
Remove need for a formatter base class
Make output paths consistently relative to base.
Add format/out help descriptions.
Remove short options for format/out.
Use fakefs for run/formatter specs.
Restrict display_results specs to darwin platform.
Lazy initialize formatter output.